Utilization of paraffin hydrocarbons to create a nonoxidizing and non



Patented May 26 1931 I UNITED STATES PATENT OFFICE FREDERICK J. HAIRLOW AND GEORGE R. BENZ, OF BARTLESVILLE, OKLAHOMA, AS-

SIGNORS TO PHILLIPS PETROLEUM COMPANY, OF BARTLESV'ILLE, OKLAHOMA, A

CORPORATION OF DELAWARE UTILIZATION OF PARAFFIN HYDROCARBONS TO CREATE A NONOXIDIZING AND NON- SULPHUROUS ATMOSPHERE IN THE TEMPERATURE TREATMENT OR SOLIDS No Drawing. I

This invention relates to the treatment of metals and the like and especially to theannealing, carburizing, carbonizing, case har lening. cementation, recarburization, forging and the like of metals and other solid articles. v

In treating such articles in the course of manufacture, they are subjected to the products of combustion in certain cases for heating the same; in other cases they are subjected to carbonaceous materials; and in certain instances such articles are subjected to a non-oxidizing atmosphere during the heating or cooling treatments.

Heretofore, the heating or cooling has been accomplished in certain cases in an atmosphere created by the use of various combustible materials, including artificial gases and natural gas. Where such gases are employed, they frequently contain sulphur or sulphurous compound and these substances have a deleterious effect on the articles undergoing treatment.

As one instance of such a treatment, reference may be made to the bright annealing of metals. In the old method of bright annealin of metals, sometimes referred to as deoxidizing, the annealed charge of, metal is cooled in an atmosphere of natural or manufactu'redgas. The gas is kept at a suflicient pressure and surrounds the charge of metal to exclude all air during this cooling period,

thus producing a bright or non-oxidized product. With such a method as this, the natural or manufactured gas may contain substances, such as sulphur or the like which will 'have a deleterious effect on, the metal undergoing treatment.

Also if manufactured gas is used, it is necsary, because of the impurities therein, to subject it to a chemical cleaning and washing process before using it for bright annealing.

It also happens in certain instances that natural or manufactured gas is not available for such treatments. Y

The primary object of the present invention is to furnish a novel system for use in such instances as this In the new method paraflin hydrocarbons, such as butanes, pro pane or ethane, are placed in liquefied form Application filed may as, 1928. Serial No. 280,647.

in gas tighttanks or drums and shipped to the point of consumption... Such hydrocarbons are within a range having a vapor pressure of not less than 25 pounds per square inch, and not greater than 500 pounds per square inch at ordinary temperatures. This liquefied gas may then be employed in the treatment of the metals or other solid articles and in use, the pressure will be released so that the "liquefied gas will assume gaseous form during utilization.

It may be burned with air for the heat treatment of solid articles such as metal, or it may be used as the surrounding atmosphere in carburization, annealing or the like. As the liquefied gas may be stored in drums, such drums may be transported with the articles while the latter are undergoing treatment or being transported from one treating unit to another, and when said gaseous parafiin hydrocarbons are employed in such treatments, the atmosphere about the articles bein treated will benon-oxidizing and non-sulp urous.

In carburizing, it has been the usual practice, heretofore, to place the articles to be treated within a box or the like and to pack around the articles a carburizing substance consisting of about equal'parts of wood charcoal and metallurgical coke. The box is then placed in a' furnace and maintained at 1600 F. for twenty-four hours or longer, and the fuel used is oil.

The present invention eliminates the necessity of employing boxes or wood charcoal and metallurgical coke, as the liquefied gas used in the new method permits the maintenance of a proper reducing atmosphere and enables the same to be easily and accurately controlled, because of the pure hydrocarbon or hydrocarbons forming part of the fuel.

In such a method it will be understood that the hydrocarbon or hydrocarbons of the fuel furnish the carbon necessary for carburiza tion.

As another example, it may be pointed out that in certain manufacturing processes necessary to the production or formation of articles made of ferrous or non-ferrous metals, abnormal stresses are set up in the body of the material of which the product is we .if in a very made These forming operations also change the internal structure of the metal. To equalize the internal structure of the metal and to relieve it after said internal abnormal stresses, it is necessary to subject the formed product to a heating process which raises the temperature of the material of which the object is formed to its critical point. At this temperature, all internal stresses are equalized and the molecular structure of the material is in equilibrium. It is now only necessary to control the rate of cooling the product from the critical temperature to atmospheric temperature. If the heating and cooling operations are conducted in an atmosphereof air. appearance of the product is affected by the action of the oxygen in the air and also in the products of combustion of the burners, where the fuel used contains sulphur and sulphurous compounds.

As before stated, the present invention contemplates the use as a fuel of certain paraffin hydrocarbons of exceptional purity for the heat operations. Such fuel will have the following advantages:

First, these hydrocarbons of the paraffin series have a very simple molecular structure, the general formulae of this group being CNH N+2 and is 100% combustible: It is possible to attain a sulphur free product in the manufacture of a fuel ofthis nature.

Therefore, the products of combustion will be water, va or, carbon dioxide, nitrogen;

iglrstate of purity. Second, by properly proport-ioning the gas air ratio, it is possible to produce by combustion an atmosphere which contains no free oxygen. This fact will insure an atmosphere in the heat zone, providing'no scc nd ary air is allowed to enter the furnace, which will preclude any possibility of the oxidation of the product being heated. The oxidation of the material is one of the causes for the necessity of a great deal of refinishing work which will be eliminated if the atmosphere in the heating zone is kept free from oxygen.

Third, this fuel free of sulphur, or other elements and com ounds of detrimental ele ments is highly a aptable to any process for the heat treatment of metals or other solids requiring an uncontaminated atmosphere in the heat zone.

combustion taken from the heating zone in which said parafiin hydrocarbons are burned. This procedure will insure the retaining of the finished'or surface appearance of the product. This method of cooling will simplify the finishing of the product, and in many cases entirely eliminate the necessity of a final finishing process.

From the foregoing, it is apparent that gaseous paraffin hydrocarbons, such as butanes, propane and ethane, may advantageously be employed in the creation of a dcsirable atmosphere for the heat or'cooling treatments of metals and other solids and by storing such paraflin hydrocarbons in liquid. form, they are available for use in isolated localities where it is not possible or feasible to pipe the same from a suitable source of supply.

It will be understood in the present invention that these liquefied paraffin hydrocarbons will be fed into the chamber containing the article or articles undergoing treatment, in regulated amounts, depending on the kind of treatment the articles are undergoing at any particular time.

What is claimed and desired to be secured by Letters Patent:

A method of thecharacter described, comprising releasing a super-atmospheric pressure from a liquefied normally gaseous paraffin hydrocarbon fluid having a vapor pressure of not less than 25 pounds per square inch and not greater than 500 pounds per square inch at ordinary temperatures and permitting the same to assume gaseous form. and then utilizing the resulting gas free of any oxidizing agent for maintaining a nonoxidizing and non-sulphurous atmosphere about metal undergoing thermal treatment.

FREDERICK J. HARLOW. GEORGE R. BENZ. 

